Expansible mold



Nov. 17, 1936.

E. E. w. BOWEN 2,061,137 EXPANSIBLE MOLD Filed Oct. 14, 1935 I r; 7-7 I r .2, 3 I I Z 7 I 6 8 4 v7 7 C, 70', 1 .7] 77 i 92 Patented Nov. 17, 1936 T QFFICE 7 Claims.

My invention relates to molds for plastic material and in particular to expansible molds.

An object of my invention is to devise a mold having readily separable parts whereby the sides of the mold may be removed in a direction at right angles to the faces of the molded product thereby preventing damage to the molded article.

My invention has particular utility in connection with the molding of cement cubes which are to be used for testing the properties of cement. In the making of these test cubes it is highly desirable that the dimensions of the cube be accurate and that the corners should remain sharp and unbroken. In one form or" mold used heretofore for molding cement cubes, the mold has been divided along a diagonal of one face of the cube, thus leaving one corner of the cube to 'be formed in each half of the mold and the two remaining corners to be formed along the dividing line of the mold. In such an arrangement it has been difficult to obtain a mold which will produce good sharp corners and at the same time maintain the correct angular relations between the sides of the cube.

In the formation of my cube mold, I assemble the mold from accurately machined lengths of bar material, and by so doing, I am able to maintain the adjacent sides of the mold accurately at right angles to each other and to produce sharp corners.

The mold which I have devised is formed in two separable halves which cooperate to form the four vertical sides of a cube while the bottom face of the cube is formed against the surface which supports the mold and the top face is formed by leveling ofi the plastic material in the mold. Each half of the mold is formed of one side member or wall with an attached end wall and one or more transverse walls. The transverse walls are arranged in pairs (one from each half) forming transverse partitions between the cube spaces, and provision is made so that when the halves are separated the cube spaces will be expanded in two directions to free the cubes.

Two forms of my invention are illustrated in the accompanying drawing in which:

Figure l is a plan view of one form of my expansible mold shown in closed position;

Figure 2 is a vertical section of Figure 1 taken along line 2-2;

Figure 3 is a plan view of the mold of Figure 1 showing the mold in expanded position;

Figure 4 is an enlarged fragmentary sectional View of Figure 1 taken along line 4-4 illustrating cured to side wall I.

the clamping arrangement employed in the mold;

Figure 5 is a plan view of a second arrangement of mold according to my invention showing the mold in closed position; and

Figure 6 is a plan view of the mold of Figure 5 shown in expanded position.

Referring to Figure l, I have shown a mold for forming three cubes in the spaces A, B and C. The mold proper is formed of two side members I and 2, end members 3 and 4, and transverse walls 5, 6, l and 8. All of these members are preferably formed of pieces of cold-rolled steel having their ends accurately machined. End wall 3 is permanently secured to side wall 2 in any suitable manner, and end wall 4 is likewise se- Also, transverse walls 5 and 'l are secured to side wall I, while transverse walls 8 and 8 are secured to side wall 2. Side wall I, end 4 and transverse walls 5 and 1 form one half of the mold, while side wall 2, end wall 3 and transverse walls 6 and 8 form the other half of the mold.

One manner of securing the end walls and transverse walls to the side walls is illustrated in Figure 2. In this figure, the transverse wall 7 is shown secured to the side i by means of a screw 1a, and dowel pins lb are provided to accurately position the wall I in a vertical plane and to prevent its rotation about the axis of screw la. Another dowel pin 10 is carried by the '30 front edge of the wall I and engages a hole formed in side member 2 to accurately position the free end of the wall. Two thumb screws 9 and i0, one carried by each side member, are provided for clamping together the two halves of the mold.

The manner in which the thumb screws are mounted in the side walls is illustrated in Figure 4 where it will be seen that the screw ID has a reduced shank section Him by which it is journaled in the side member 2 and an enlarged screw section 10b which prevents removal of the screw from wall 2. Dowel pins 4a are provided in the end wall 4 and cooperate with holes formed in the side wall 2 for the purpose of accurately positioning the end 4 with respect to the side wall 2. The screw head lb of the screw Ill engages a threaded bore formed in the end of the end wall 4 and serves as a clamp for clamping together side wall 2 and end wall 4. It will be observed that by 50 the arrangement illustrated in Figure 4 the screw It not only serves as a clamp for securing the two halves of the mold together, but after the screw Iii has been backed off a short distance, the enlarged screw head lOb engages the bottom of 5 5 the counter-bore in side wall 2 and continued rotation of the screw forces the side wall 2 away from the end wall 4.

From Figure 1, it will be observed that the transverse walls are arranged in pairs 56 and 1 8 forming transverse partitions between mold compartments A, B and C, and the right hand transverse wall of each compartment is formed by either a transverse wall or an end wall of one half-section of the mold, while the left hand transverse wall of each compartment is formed by the other half-section. It will also be observed that the two walls of partitions 5-6 and l8 located between adjacent pairs of compartments are separated by small spaces H. The presence of these spaces permits enlargement of the molding compartments in a longitudinal direction when the screws 9 and H) are released, and, since release of the screws also permits the side walls I and 2 to be separated, the arrangement permits each mold compartment to be expanded in two directions for freeing the cubes. The manner in which the compartments are expanded when the screwsare released is clearly shown in F ure 3- Instead of using transverse walls of uniform thickness with the intervening space H to form the. transverse partitions as in Figures 1 and 3, the partitions may be formed with transverse walls having a tapering width as shown at 5, 6, 7 and 8 in Figures 5 and 6. In this arrangement the transverse walls are of greater width at the end where they are secured to side walls and taper in width towards the free end. Due to the tapered shape of the walls in this arrangement, separation of the two half-sections permits a limited longitudinal movement of the two sections with respect to each other, as well as lateral movement, thereby expanding the mold compartments in two directions.

One advantage of the arrangement shown in Figure 5 is that the two walls forming the partitions located between each pair of compartments may be spaced very close together so that plastic material will not become lodged between these walls and interfere with the proper operation of the mold. In the arrangement of Figure 1 plastic material is likely to enter the spaces II and, unless it is removed, will prevent proper expansion of the mold. However, the spaces Il may be filled with a suitable filler material before using the mold which may be easily removed when it is desired to expand the mold. Also, suitable shim or filler elements may be inserted in the, spaces ll while the mold is being filled and then removed when the mold is to be expanded.

If desired, a small space may be provided between the walls forming the partition in the mold shown in Figures 5 and 6, like space I I in Figure L In using the molds of my invention, they are placed upon a smooth surface in the positions shown in Figures 1 and 5. The cube spaces A, B and C are then filled with plastic material and the top surfaces are smoothed oil level with the t p of the mold. After the material has had time to set, screws 9 and I0 are loosened, and if the mold does not immediately break away from the cubes, continued backing-off of screws 9 and ID will force the half-sections apart. A little tappingof the mold after the screws have been loosened will help in freeing the cubes. It will be noted that in both forms of my invention, the two half-sections must be separated far enough to disengage the dowel pins 4a and lo before the mold compartments can be expanded longitudinally of the mold, but this requires only a limited separation, and, after the pins have been disengaged, the two half-sections may be shifted to expand all the compartments longitudinally of the mold, and thereafter the two half-sections may be completely separated without any binding between the mold parts and the cubes and without danger of breakage of the cubes.

One advantage of forming the mold of separate parts of bar material secured together is that in the event of injury to either side wall of the mold, the mold may be dismantled and the injured surface machined to proper condition without having to replace the entire mold or half-section. While I prefer to use the construction herein illustrated, it will be understood that the two half-sections may be formed by casting the end wall and transverse walls integral with the side wall if desired.

While the mold of my invention is especially useful for making cement cubes for testing purposes, it will be understood that it is not limited to such use, and the principle of my invention may be applied to molds for other purposes.

I have herein described the principle of my invention and illustrated two embodiments thereof. Various modifications will occur to those skilled in the art, and I desire it to be understood that all modifications which fall within the terms of the appended claims are to be considered as falling within the scope of my invention.

What I claim is:

1. An expansible mold comprising two separable half-sections, each comprising a side wall having attached thereto a plurality of transverse walls spaced along the length thereof, and means for separably clamping together said half-sections to form a plurality of mold compartments, adjacent compartments being separated by a double-walled partition formed of one transverse wall supported by one side wall and another transverse wall supported by the other side wall, the right hand transverse walls of all compartments being carried by one half-section, while the left-hand transverse walls of all compartments are carried by the other half section, said transverse walls being arranged so that upon limited separation of said side walls, relative longitudinal movement of the side walls is permitted in a direction to expand each of said mold compartments longitudinally of said mold.

2. An expansible mold comprising two side walls, an end-wall secured to one side wall, a second end wall secured to the other side wall, means for separably clamping together said walls to form a molding frame, transverse partitions for dividing said frame into a number of mold compartments, each transverse partition being formed of a transverse wall carried by one side wall and a second transverse wall carried by the other side wall, the two walls forming each of said transverse partitions being spaced apart to permit expansion of said compartments longitudinally of said mold.

3. An expansible mold comprising two side walls arranged in spaced parallel relation, transverse partitions arranged between said side walls to form a plurality of mold compartments, each partition being formed of two transverse walls, the right-hand wall of each compartment being secured to one side wall and the left-hand wall of each compartment being secured to the opposite side wall, said transverse walls of each partition being spaced apart, whereby relative longitudinal movement between said side walls permits each compartment to expand longitudinally of said mold.

4. An expansible mold comprising a rectangular frame formed of two separable half-sections, each section comprising a side wall having attached thereto a plurality of transverse walls spaced along the length thereof, means for separably clamping together said half-sections to form a plurality of mold compartments with a doublewalled transverse partition between adjacent compartments, the right-hand wall of each compartment being formed of a transverse wall carried by one half-section and the left-hand wall of each compartment being formed by a transverse wall carried by the other half-section, and means rendered effective upon partial separation of said half-sections for permitting relative longitudinal movement between said half-sections in a direction to expand each of said compartments longitudinally of said mold.

5. An expansible mold comprising a rectangular frame formed of two separable half-sections, each section comprising a side wall having attached thereto a plurality of transverse walls space along the length thereof, means for separably clamping together said half-sections to form a plurality of mold compartments with a doublewalled transverse partition between adjacent compartments, the right-hand wall of each compartment being formed of a transverse wall carried by one half-section and the left-hand wall of each compartment being formed by a transverse wall carried by the other half-section, means carried by one half-section and cooperating with the other half-section for preventing relative longitudinal movement between said half-sections when clamped together, said means becoming disengaged upon limited lateral separation of said half-sections, and the walls of said transverse partitions being arranged so that upon the release of said means limited longitudinal movement between said half-sections is permitted in a direction to expand each of said compartments longitudinally of said mold.

6. An expansible mold comprising a rectangular frame formed of two separable half-sections, each section comprising a side wall having attached thereto a plurality of transverse walls spaced along the length thereof, means for separably clamping together said half-sections to form a plurality of mold compartments with a doublewalled transverse partition between adjacent compartments, the right-hand wall of each compartment being formed of a transverse wall carried by one half-section and the left-hand wall of each compartment being formed by a transverse wall carried by the other half-section, positioning means carried by one half-section and cooperating with the other half-section for preventing relative longitudinal movement between said half sections when clamped together, said means becoming disengaged upon limited lateral separation of said half-sections, the adjacent faces of the two walls of each transverse partition being oppositely tapered whereby upon the release of said positioning means limited longitudinal movement between said half-sections is permitted in a direction to expand each of said compartments longitudinally of the mold.

7. An expansible mold comprising a rectangular frame formed of two separable half-sections, each section comprising a side wall having attached thereto a plurality of transverse walls spaced along the length thereof, means for separably clamping together said half-sections to form a plurality of mold compartments with a doublewalled transverse partition between adjacent compartments, the right-hand wall of each compartment being formed of a transverse wall carried by one half section and the left-hand wall of each compartment being formed by a transverse wall carried by the other half-section, the adjacent faces of the two walls of each transverse partition being oppositely tapered whereby upon partial separation of the two half-sections limited longitudinal movement between said half-sections is permitted in a direction to expand each of said compartments longitudinally of the mold.

EDGAR E. W. BOWEN. 

